HDR10 and Dolby Vision are two HDR formats that are commonly found in 4K Blu-ray players. HDR10 is an open standard that uses static metadata, which means that the brightness and color information is applied to the entire video signal. On the other hand, Dolby Vision uses dynamic metadata, which adjusts the brightness and color information on a scene-by-scene or even frame-by-frame basis. This allows for a more precise and nuanced image. Additionally, Dolby Vision has a higher peak brightness and a wider color gamut than HDR10, which can result in a more vivid and lifelike picture. However, not all TVs support Dolby Vision, so it's important to check compatibility before purchasing a 4K Blu-ray player. Ultimately, both HDR10 and Dolby Vision can provide a significant improvement in picture quality over standard Blu-ray, so it's worth considering a player that supports both formats to get the most out of your 4K Ultra HD discs.